This invention relates to a grinding tool for grinding a material to be ground (hereinafter referred to as "ground material") represented by a hard and brittle material (hereinafter referred to as "brittle material") such as glass or ceramic, a metal material, or the like, and more particularly to an ultrasonic vibration composite grinding tool for grinding a ground material while applying vibration to the material during grinding of the material.
In order to ensure satisfactory grinding of a ground material such as a brittle material, a metal material or the like into a predetermined or desired size by infeed and permit a surface of the ground material which has been subject to grinding or processing to exhibit properties of a desired level, it is required to reduce grinding force which is applied to the ground material during the grinding, to thereby permit a grinding wheel to exhibit a satisfactory grinding performance, resulting in eliminating dressing as much as possible.
In general, when a vibrator is used to apply vibration to a grinding wheel, an increase in diameter of the grinding wheel to a degree as large as, for example, 100 mm or more renders smooth grinding substantially impossible. This causes advantages such as a reduction in grinding force and the like obtained due to the vibrator to be lost.
A substrate such as a glass substrate for a liquid crystal display device, a glass substrate for a plasma display device, a glass substrate for a thermal head, a ceramic substrate for a hybrid IC or the like tends to be increased in size with the years. Unfortunately, a grinding tool for uniformly grind a surface of the substrate at an increased speed has not been developed in the art.